get value from previous row

Hi , Anonymous 

According to your description, you want to "get value from previous row".

First , you need to sort the [DateTime] in Power Query and you need to check the [DateTime] is single value in each row. IF not , you need to add an index column in Power Query Editor as a row number to judge .

Here, i use your [DateTime] as a row number to check which row is calculating.

Then we can click "New Column" to add a calculated column by this dax code:

Column = var _cur_row = [DateTime]
var _t =ADDCOLUMNS( FILTER('Table' , 'Table'[DateTime]<= _cur_row) , "cal" , [IN] - [OUT])
return
SUMX(_t ,[cal])

Then we can meet your need:

Thank you for your time and sharing, and thank you for your support and understanding of PowerBI! 

Best Regards,

Aniya Zhang

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hi Anonymous 

you may also add a calculated column like:

INSIDE2 = 
SUMX(
    FILTER(
        TableName, 
        TableName[DateTime]<=EARLIER(TableName[DateTime])
    ),
    TableName[IN] - TableName[OUT]
)

it worked like: